Andy Murray was given a stern examination by Denis Istomin on Friday, as the reigning US Open champion was forced to step up his game as he booked his place in the semi-finals of the Brisbane International.

Muray, continuing his preparations for the forthcoming Australian Open, was given no quarter by Istomin - who ran his opponent hard before ultimately coming up narrowly short in a 6-4 7-6(3) victory for the Scot.

Istomin had been responsible for one of the upsets of tournament prior to Friday's meeting, after dumping home favourite Lleyton Hewitt out of the competition. And he had his chances to do the same to Murray - creating two break opportunities in the first set, and engineering a lead in the second set tiebreak - but was ultimately unable to close any of those openings out.

Much of that was down to Murray who, with coach Ivan Lendl watching dispassionately from stands, seemed to raise his game at key stages to prevent the contest going on longer than the 97 minutes it lasted.

Murray did not sparkle in the opening set, with Istomin creating two break point opportunities early on. But the Olympic champion saved both of those before converting the first opening he created - and that was enough to put the first set to bed.

The second set saw the tension increase, with both players proving impenetrable on serve as the tie headed inexorably to a tiebreak. Istomin must have initially thought he was going to send the match to a deciding set when he raced into an early 2-0 lead, but Murray erased that almost immediately - reclaiming the advantage with a pinpoint forehand.

That seemed to break the Uzbeki's resolve, and Murray soon finished off the contest - with a timely challenge overturning what could have been a slight wobble and setting him up to move into the last four with a concluding forehand into the open court.

Murray will now face Kei Nishikori for a place in the final, after the Japanese fifth seed overcame Alexandr Dolgopolov by an identical scoreline.

The other semi-final sees Marcos Baghdatis face Grigor Dimitrov - after the two men defeated third seed Gilles Simon and seventh seed Jurgen Melzer respectively.

Dimitrov cruised to victory against his Austrian opponent - needing just 57 minutes to clinch the 6-3 6-2 triumph - but Baghdatis had to work a bit harder, requiring 90 minutes to finally put Simon to bed in a 6-3 6-4 win.